Well I must admit the table of contents for Bagonzi's book looks decent. But my knowledge of him comes from some instructional video clips that are on the Internet and, based on those, I don't care for what he teaches. Again, just my opinion.
As for books I'd recommend...
The Art and Science of Pitching - This is the latest book on mechanics by Tom House
The Louisville Slugger Complete Book of Pitching - Been a while since I read this but I thought it was one of the better books out there at the time.